Pulmonary Ventilation II

Question 1

What is tidal volume?

Answer 1

Amount of air in a single inspiration or expiration (500ml)

Question 2

What is functional residual capacity?

Answer 2

Volume of air that remains in the lungs at the end of normal respiration (2,400ml)

Question 3

What is vital capacity?

Answer 3

Volume of air that can be exhaled after a maximal expiration (4800ml)

Question 4

What is residual volume?

Answer 4

Amount air remaining in the lungs after maximal expiration (1,200ml)

Question 5

What is total lung capacity?

Answer 5

Maximum volume of air in the lungs after a maximal inspiration (6000ml)

Question 6

What is airflow resistance?

Answer 6

Resistance of the respiratory tract to airflow during inhalation and expiration

Question 7

What is airway resistance influenced by?

Answer 7

Diameter of the airways
Laminar or turbulent airflow
Airway resistance is not constant

Question 8

What is the most common pulmonary function test?

Answer 8

Spirometry

Question 9

What does spirometry measure?

Answer 9

• effort
• the amount/volume
• speed/flow of air that can be inhaled and exhaled

Question 10

How do you perform spirometry?

Answer 10

Deepest breath in
Exhale not sensor as hard and fast as possible, for as long as possible, at least 6 seconds
Followed by rapid inhalation

Question 11

What is FEV1 forced expiration volume in one second?

Answer 11

Volume of air that can forcibly be blown out in one second, after full inspiration measured in litres

Question 12

What is FVC forced vital capacity?

Answer 12

Volume of air that can forcibly be blown out after full inspiration measured in litres

Question 13

What s normal FEV1/FVC ratio?

Answer 13

0.7-0.8

Question 14

What is FEV1 % and FVC %predicted?

Answer 14

Both are > or equal to 80%

Question 15

How do you measure FEV1% and FVC%?

Answer 15

FEV1 % and FVC% predicted are the measured FEV1 and FVC of the patient divided by the average FEV1 and FVC in the healthy population for any person of similar age, height and gender

Question 16

What are the spirometry outcomes?

Answer 16

1. Normal
2. Obstruction (obstructive disease)
3. Restriction (restrictive disease)
4. Mix obstruction and restriction

Question 17

What is the FEV1/FVC ratio in obstructive disease?

Answer 17

<0.7

Regardless of FEV1% and FVC% predicted

Question 18

What are diseases associated with airflow obstruction?

Answer 18

COPD
Asthma - uncontrolled
Bronhiectasis
Cystic fibrosis

Question 19

What is the FEV1/FVC ratio in restrictive disease?

Answer 19

> 0.8

FEV1 % predicted and FVC % predicted : reduced <80%

Question 20

What are diseases associated with a restrictive defect?

Answer 20

Pulmonary - lung fibrosis, pulmonary oedema

Extrapulmonary - obesity, pregnancy, neuromuscular disorders

Question 21

What are the results in mixed obstructive and restrictive disease?

Answer 21

FEV1/FVC ratio usually normal
FEV1 <80% predicted 
FVC: < 80% predicted
• Clinical history is important
 • E.g. co-existent COPD and pulmonary fibrosis

Question 22

What is the clinical application of spirometry?

Answer 22

• Diagnosis of respiratory disease
• Provide severity levels for a number of
respiratory conditions, e.g. COPD
• Evaluate progress of respiratory diseases • Treatment response

Question 23

What are the limitations of spirometry?

Answer 23

• Dependent on patient cooperation and effort
• Since results are dependent on patient cooperation, lung volume
(FVC) can only be underestimated, never overestimated
• Usually repeated at least three times to ensure reproducibility, each FVC result within 5% or less than 150 ml variation
• Stable asthmatics have normal spirometry between acute exacerbation, limiting spirometry’s usefulness as a diagnostic tool
• Look at the flow volume loop to assess quality and effort of the test (not always available in some commercial spirometers)

Question 24

What are inspiratory muscles?

Answer 24

Diaphragm
External intercostal muscles
Accessory muscles of inspiration

Question 25

What are forced expiratory muscles?

Answer 25

Muscles in the abdominal wall
- rectus abdominis
- internal and external obliques
- transversals abdominus
Internal intercostal muscles

Question 26

What can respiratory muscle strength be assessed by?

Answer 26

– maximal inspiratory pressure (MIP or PImax) – maximal expiratory pressure (MEP or PEmax)

Question 27

What does maximal inspiratory pressure reflect?

Answer 27

The strength of inspiratory muscles

Question 28

What does maximal expiratory pressure reflect?

Answer 28

Strength of expiratory muscles